Luminaire



Nov. 8, 1966 K. FRANCK 3,284,526

LUMINAIRE Original Filed April 9, 1958 5 Sheets-5heet 1 Pew? 4e7- //ous37-2557 5/05 S/DE 58 !NVENTOR '31 A zmrFqwA/ck ATTORNEYS K. FRANCK Nov.8, 1966 LUMINAIRE 3 Sheets-Sheet 2 Original Filed April 9, 1958 INVENTORA/URTFIPAV/VC'A M9 agf7 ATTORNEYS Nov, 8, 1966 K. FRANCK 3,

LUMINAIRE Original Filed April 9, 1958 3 Sheets sheet 3 INVENTOR'ATTORNEYS tern 3,284,62 Patented Nov. 8, 196

This case is a continuation of application, Serial No. 306,970, filedJuly 24, 1963, now abandoned, which was itself a continuation ofapplication Serial No. 727,352,

, filed April 9, 1958, now abandoned.

' This invention relates in general to luminaires and particularly to anew and useful street luminaire having a novel construction andarrangement of reflector and retractor for effecting even lightingdistribution over a wide street area.

While not specifically limited thereto, the present invention findsparticular application for use with a street luminaire having a linearlight source, preferably a mercury lamp, and in which a substantiallyellipsoidallyshaped-reflector and refractor are arranged with theirlongitudinal axes transverse of the street. With luminaires of thisgeneral type, it is usual to assign a large area of reflector andrefractor t the generation of a high candle-power beam of substantiallyparallel light rays for illuminating areas on the street remote from theluminaire.

Previously with luminaires of this type, the light patproduced was inthe nature of concentrated rectangular light sections extendingtransversely of the street at each end and remote from the luminaire,and a generally rectangular light pattern on the street directly beneaththe luminaire.

Since relatively large areas of the reflector and r fractor surfaces ofthe luminaire are assigned for the formation of the high candle-power,high angle main f light beams, the optical action or expansion of theremainder of the light by the reflector and refractor was considerablylimited to an area directly beneath the light.

Thus, luminaires of this type produced undesirable bright v light areasdirectly beneath the luminaire and rather poor distribution of lightbetween the high candle-power, wellilluminated extremities of light.

The present invention provides an improved light distribution forluminaires of this general nature by providing a novel refractorarrangement which is effective to explode or more widely distribute thearea of light pro duced directly beneath the luminaire so that it mergeswith the light produced at the extremities to effect a substantiallyuniform light distribution over a large rectangular street area.

Accordingly, it is an object of this invention to provide a luminairehaving substantially even light distribution over a large rectangularstreet area.

A further object of this invention is to provide an improved luminairehaving a combination reflector and refractor to distribute highcandle-power beams of light for V illuminating areas remote from theluminaire and having means for producing a substantially uniform lightpattern I between these remotely illuminated areas.

A further object of the invention is to provide a luminaire which isrugged in construction, simple in design and economical to manufacture.

. vantages and specific objects obtained by its use, reference should behad to the accompanying drawings and delighted areas 14 and 16 in remotelocations from the refractor surfaces are assigned to the generation ofa high the reflector and/or refractor surface becomesconsiderlipsoida'lly-shaped reflector 24 to which is aflixed a simi-.scriptive matter in which there is illustrated and described apreferred embodiment of the invention.

In the drawings:

FIG. 1 is a perspective view of a highway or street indicating thelighting pattern produced by conventional luminaire of the highcandle-power beam type;

FIG. 2 is a detailed top plan view of a refractor constructed inaccordance with this invention;

FIG. 3 is a transverse section taken on the line 3-3 of FIG. 2;

FIG. 4 is a longitudinal section taken on the line 4-4 of FIG. 2;

FIG. 5 is a schematic plan view of a portion of. the street areaindicated in FIG. 1, indicating anarrangement of refractor lens patternto effect an expansion and distribution of the highly lighted areabeneath the luminaire; and

FIGS. 6 to 8, inclusive, are schematic top plan views of refractorsindicating various continuously curving prism path arrangements toelfect the desired lighting distribution between the highly illuminatedremote light areas produced by the luminaire.

Referring to the drawings in particular, FIG. 1 shows the conventionalstreet lighting patterns produced by luminaires constructed inaccordance with the prior art. A long street 10 is provided with aluminaire 12 mounted on a pole 13. The luminaire 12 is designed toproduce a high candle-power beam of substantially rectangular luminaire.

The luminaire 12 is substantially elliptical in plan and is arrangedwith the longitudinal axis transverse of the street It). A large area ofthe luminaire reflector and candle-power beam of substantially parallellight rays to effect illumination of the remote areas 14 and 16. Smallerrectangular light areas 18 and 20, closer to the luminaire, are usuallyproduced by the lower portions of the ellipsoidally-shaped reflectors ofthe conventional street luminaires, and these light areas are shifted tolocations 14 and 16 by the action of the refractor.

In these conventional luminaires, once the design is committed toincorporate a relatively large area or reflector and refractor surfaceto the formation of the high candle-power high angle main light beams toproduce the areas 14 and 16, the optical action of the remainder of ablylocalized. Such a light distribution usually results in a spot of light22 of high illumination on the street directly below the luminaire.

A luminaire of this type comprises a generally ellarly shaped refractor26. An elongated cylindrical light source 28 would normally produce thelight patterns at the locations 18 and 20 by rays reflected betweenpoints 30 and 32 of the reflector 24. Corresponding areas 34 and 36 ofthe refractor 26 accept the parallel beam from the reflector and elevateit in such directions to spread out the high candle-power beam furtheralong the street to produce the illuminated areas 14 and 16.

The optical action of the remainder of the reflector is considerablycircumscribed in directions lengthwise of the street, transversely ofthe luminaire as shown in FIG. 3. The top section of the reflector isdesigned to spread the light reflected by it through as wide an angle aspossible. This is done by allowing some of the light reflected by thetop section of the reflector 24 to pass through the beam section of therefractor 26 as indicated by ray 40 in FIG. 3. However, it is oftenpreferable to limit emergence of this light through the bottom sectionof the refractor 26 to locations between points 9 a 42 and 44 as markedin FIG. 3. Reflected light rays 38, 46, 48 and 50 show typical ray pathsreflected from the top section of the reflector 24 and transmittedthrough the bottom section of the refractor 26.

The luminaire 12 is usually positioned in the street with itslongitudinal axis extending across the street. In FIG. 4 thelongitudinal profile of the reflector 24 is shaped to direct lightforward into the street as far as possible. The restriction in theamount of forward throw of the reflected light is given by the locationof the normal front bottom edge 52 of the reflector 24. Rays indicatedat 54, 56, 58 and 60 show the reflected path of light which is directedforward into the street. The reflector 24 is shaped to permit suflicientclearance for light rays 62 and 64, which originate at the back end ofthe linear light source 28, to clear the front edge 52 of the reflector24.

In considering the luminaire 12 as thus far described and contemplatingthe direction of the reflected rays from the top of the reflector 24simultaneously in both transverse and longitudinal directions, it can beseen that the angular range covered by the reflected rays is rathernarrow. The reflected rays would normally result in the spot of highillumination at 22 below the luminaire 12.

In accordance with the invention, the refractor 26 is of a novelconstruction which eifects a spreading of the illumination area 22longitudinally of the street to meet the illumination areas 14 and 16,and transversely of the street to cover the entire width of the streetfrom a near curb 66 to a far curb 68. It has been found, in accordancewith the invention, that the most effective way to uniformly illuminatethe entire street area between the high illumination beams 14 and 16 isby a novel arrangement of prisms on the inside surface of the refractor26. It is within the scope of this invention to include two sets ofprism-s at right angles to each other, one set on the outside of therefractor 26 and the other set on the inside. It was found, however,that regardless of whether the transverse action is accomplished on theinside and the longitudinal action on the outside, or vice versa, thatthe set of parallel prisms placed on the outside of the refractor willwork only to a limited amount and quite inefficiently.

One method of accomplishing the enlargement of the area 22 and theproduction of uniform lighting between the high beam areas 14 and 16 isindicated in FIG. 6. The lower or central portion 70 of the refractor ismade with an arrangement of prisms in continuously curved paths 72.Depending on the amount of angular light ray shift required, both intransverse and longitudinal directions, the prism path is made as asemi-circle as indicated at 72 in FIG. 6, or an elliptical path inalignment with the longitudinal axis, as indicated at 74 in FIG. 7, orwith an elliptical path in alignment with the transverse axis, asindicated at 76 in FIG. 8. With the arrangements indicated, refractivepower of the prisms may be suitably varied along the path described, toeffect the desired light ray direction and intensity to cover thecomplete street area.

In an actual luminaire refractor construction, it has been foundpractical to approximate the curve path for the prisms as indicated inFIGS. 6 to 8, inclusive, by dividing the bottom portions 70 of therefractor 26 into small areas (as indicated in FIG. 2 and on the leftside 4 of FIGS. 6 to 8 inclusive). In FIG. 2 the bottom of the refractoris divided into panels C, D, E, F, G, and H.

The individual action of these prismatic panels is shown A somewhatschematically in FIG. 5. Considering that the light rays are directed asillustrated in FIGS. 3 and 4 by the reflector 24, the spot of brilliance22 beneath the luminaire would appear as projected light divided up intothe areas covered by the prism panels C, D, E, F, G

and H corresponding to the prism panels C, D, E, F, G

" and H of FIG. 2. The prism panels are chosen in respect to prismsurface angles and orientation of the prism rows of each panel to effectthe expansion of the light through a rectangular area 80 defined on thestreet as indicated at FIG. 5. The result is a somewhat discontinuousbut thorough coverage of the entire area 80 between the highcandle-power beam areas 14 and 16.

The outside surface 82 of the refractor 26 is constructed to provide aminor amount of general diffusion via flutes 1100, in order to blend thediscontinuous patterns of the panels formed at C through H (FIG. 5) intoa smooth pattern of substantially uniform illumination throughout thearea 80. i

In the actual construction of the panel system indicated schematicallyin FIG. 5 and actually in FIG. 2, the panels C through H on therefractor inside surface need not be exactly rectangular. In plan viewthe prismatic panel section is substantially oval as at 70. Two sideportions 86 and 88 of the refractor 26 are committed to the generationof the high candle-power beam producing the illuminated areas 14 and 16.A forward section 90 is eifected to afford the projection of the lightacross the street as is a rear section 92. The individual panels Cthrough H in the oval prismatic section 84 are preferably shaped asshown in the drawing at FIG. 2. It will be noted that the panels C, Dand E are essentially rectangular while the panels F, G and H are shapedto blend at their outside edges into the adjoining prismatic beam panels86 and 88.

Thus the invention provides a luminaire having a novel constructionaffording uniform illumination between two highly illuminated remoteareas.

While a specific embodiment of the invention has been shown anddescribed in detail to illustrate the application of the inventionprinciples, it will be understood that the invention may be embodiedotherwise without departing from such principles.

What I claim is:

1. A substantially ellipsoidal refractor comprising sides and endportions and a central bottom portion extending therebetween, saidcentral bottom portion formed of a plurality of prisms arranged incontinuous curved rows, said rows being oriented to dispose said prismsfor distributing light incident thereon into a uniform elongatedrectangular area, some of said prisms extending parallel with respect tothe longitudinal center line of said ellipsoidal refractor, others ofsaid prisms extending diagonally with respect to the longitudinal centerline of said ellipsoidal refractor and further ,of said prisms extendingin said continuous curved rows from said some of said prisms and saidothers of said prisms, said further of said prisms extending in curvedpaths from one side of the longitudiial center line of said ellipsoidalrefractor to the other s1 e.

2. A substantially ellipsoidal refractor comprising sides and endportions and a central bottom portion extending therebetween, saidcentral bottom portion having a plurality of discrete prismatic panels,each including a plurality of rows of prisms arranged for deflectinglight incident thereon to an area complementary to adjacent associatedpanels for effecting uniform lighting transversely and longitudinallyover an elongated substantially rectangular area, said plurality of rowsof prisms in one of said descrete prismatic panels extending centrallyof said refractor and parallel with the longitudinal axis thereof, saidplurality of rows of prisms of others of said discrete prismatic panelsextending on either side of said one panel and diagonally relative tothe longitudinal center line of said ellipsoidal refractor, saidplurality of rows of prisms of another of said discrete prismatic panelsextending transversely relative to the longitudinal center line of saidellipsoidal refractor from one side of said central bottom portion tothe other and curving along their lengths toward said plurality of rowsof prisms of said one said others of said panels on either side of thelongitudinal center line of said ellipsoidal refractor. I

3. In a luminaire for street lighting and the like, and including anextended linear light source, a reflector including a portion positionedabove said light source, said reflector being substantially ellipticalin horizontal section and shaped to direct a large portion of light fromsaid light source laterally and remotely of said luminaire intoconcentrated beams on each side thereof and the remainder downwardly, arefractor positioned below said reflector and arranged to enclose thebottom of said reflector, said refractor being substantiallyellipsoidal; said refractor having sides and end portions and a centralbottom portion extending therebetween, a plurality of prisms on saidcentral bottom portion, some of said plurality of prisms extending fromone end of said bottom portion in parallel paths and parallel to thelongit-udinal center line of said ellipsoidal refractor and on eitherside thereof, others of said plurality of prisms on either side of saidfirst mentioned prisms extending dia gonally relative to thelongitudinal center line of said ellipsoidal refractor, said pluralityof prisms including further prisms extending from said first and secondmentioned plurality of prisms in curved paths contiguous with said firstand second named plurality of prisms from one side of the longitudinalcenter line of said ellipsoidal refractor to the other, said prismsdistributing light incident thereon from said light source and from saidrefractor uniformly between the concentrated beams on either side ofsaid luminaire.

4. In the luminaire of claim 3, wherein said paths of said prisms arearranged along substantially semicircular curves.

5. In a luminaire for street lighting and the like, and including alight source, a substantially ellipsoidal reflector above the lightsource shaped to direct a large portion of light from said sourcelaterally and remotely of said luminaire into concentrated :beams oneither side thereof and the remainder downwardly, an elongated refractorshaped to enclose the bottom of said reflector; said refractor havingsides and end portions and a central bottom portion extendingtherebetween, said central bottom portion being formed with a pluralityof prisms extending longitudinally and diagonally on either side of thelongitudinal center line of said refractor at one end thereof andtransversely of said central bottom portion at the other end in curvedrows contiguous with the longitudinally and diagonally extendingportions thereof and distributing light from said light source uniformlybetween the concentrated light beams on either side of said luminaire.

6. In the luminaire of claim 5, wherein said central bottom portion isformed with a plurality of discrete prismatic panels and each of thepanels is constructed and arranged to deflect light to an areacomplementary to other associated panels and all of the panels inconcert eifect substantially uniform light distribution between saidconcentrated beams.

7. In the luminaire of claim 6, wherein said prismatic panels are formedon the light source side of said refractor and means are provided on theoutside of said refractor to diffuse said light directed bycomplementary panels to effect overlapping and uniformity throughout thelighted area.

8. For use in a luminaire having a reflector and a light source; asubstantially ellipsoidal refractor comprising downwardly extendingsides and end portions and a cen tral bottom portion extendingtherebetween at the lowermost portions thereof, said sides comprisingmeans for receiving parallel beams from said reflector and forvertically redirecting the same, said central bottom portion beingsubstantially horizontally orientated and including means for receivingdown light from the reflector and light source and for distributinglight incident thereon into a substantially uniform elongatedrectangular area, said means being at least partially formed of aplurality of prisms arranged in continuous substantially curved rows,for distributing light incident thereon into a uniform elongated betweenthe beams, some of said substantially curved rows of prisms beinggenerated about axes per pendicular to a generally horizontal plane andextending in paths from one side of the longitudinal center line of saidellipsoidal refractor to the other side.

9. The ellipsoidal refractor of claim 8 wherein the curvilinearity ofsaid substantially curved rows of prisms forming said central bottomportion and extending in paths from one side of the longitudinal centerline to the other side thereof is approximated in the form of discretesets of prisms, the prisms of a pair of discrete sets c0nvergingdiagonally from the sides of said refractor toward one end thereof, andanother set of prisms adjacent said one end of said refractor extendingfrom and between the prisms of said pair of discrete sets of prismsacross the longitudinal center line of said refractor.

10. The ellipsoidal refractor of claim 8, wherein said curved rows ofprisms are positioned adjacent one of said end portions and said lightreceiving and distributing means further include rows of prismsextending in rectilinear diagonal paths adjacent the other of said endportions on either side of the longitudinal. center line of saidellipsoidal refractor.

11. The ellipsoidal refractor of claim 8, wherein said curved prisms arepositioned adjacent one of said end portions and said light receivingand distributing means further include rows of prisms adjacent the otherof said end portions extending in rectilinear paths parallel to and oneither side of the longitudinal center line of said ellipsoidalrefractor.

References Cited by the Examiner UNITED STATES PATENTS 2,566,126 8/1951Franck 240-25 2,945,945 7/ 1960 Rex 240-25 3,189,739 6/1965 McPhail240l06 X NORTON ANSHER, Primary Examiner.

C. R. RHODES, Assistant Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,284,626 November 8, 1966 Kurt Franck It is hereby certified that errorappears in the above numbered patent requiring correction and that thesaid Letters Patent should read as corrected below.

Column 4, line 63, for "descrete" read discrete line 73, after "one"insert and column 6, line 19, before "between" insert rectangular areaSigned and sealed this 12th day of September 1967.

(SEAL) Attest:

ERNEST W. SWIDER EDWARD J. BRENNER Attesting Officer Commissioner ofPatents

8. FOR USE IN A LUMINAIRE HAVING A REFLECTOR AND A LIGHT SOURCE; ASUBSTANTIALLY ELLIPSOIDAL REFRACTOR COMPRISING DOWNWARDLY EXTENDINGSIDES AND END PORTIONS AND A CENTRAL BOTTOM PORTION EXTENDINGTHEREBETWEEN AT THE LOWERMOST PORTIONS THEREOF, SAID SIDES COMPRISINGMEANS FOR RECEIVING PARALLEL BEAMS FROM SAID REFLECTOR AND FORVERTICALLY REDIRECTING THE SAME, SAID CENTRAL BOTTOM PORTION BEINGSUBSTANTIALLY HORIZONTALLY ORIENTATED AND INCLUDING MEANS FOR RECEIVINGDOWN LIGHT FROM THE REFLECTOR AND LIGHT SOURCE AND FOR DISTRIBUTINGLIGHT INCIDENT THEREON INTO A SUBSTANTIALLY UNIFORM ELONGATEDRECTANGULAR AREA, SAID MEANS BEING AT LEAST PARTIALLY FORMED OF APLURALITY OF PRISMS ARRANGED IN CONTINUOUS SUBSTANTIALLY CURVED ROWS,FOR DISTRIBUTING LIGHT INCIDENT THEREON INTO A UNIFORM ELONGATED BETWEENTHE BEAMS, SOME OF SAID SUBSTANTIALLY CURVED ROWS OF PRIMS BEINGGENERATED ABOUT AXES PREPENDICULAR TO A GENERALLY HORIZONTAL PLANE ANDEXTENDING IN PATHS FROM ONE SIDE OF THE LONGITUDINAL CENTER LINE OF SAIDELLIPSOIDAL REFRACTOR TO THE OTHER SIDE.